一张图看懂 SQL 的各种 join 用法
下图展示了 LEFT JOIN、RIGHT JOIN、INNER JOIN、OUTER JOIN 相关的 7 种用法。具体分解如下：1.INNER JOIN（内连接）SELECT FROM Table_A AINNER JOIN Table_B BON A.Key = B.Key2.LEFT JOIN（左连接）SELECT FROM Table_A ALEFT JOIN Table_B BON A.Key = B.Key3.RIGHT JOIN（右连接）SELECT FROM Table_A ARIGHT JOIN Table_B BON A.Key = B.Key4.OUTER JOIN（外连接）SELECT FROM Table_A AFULL OUTER JOIN Table_B BON A.Key = B.Key5.LEFT JOIN EXCLUDING INNER JOIN（左连接-内连接）SELECT FROM Table_A ALEFT JOIN Table_B BON A.Key = B.KeyWHERE B.Key IS NULL6.RIGHT JOIN EXCL
